Chromatography ligand

ABSTRACT

The present invention relates to a chromatography ligand defined by the following formula R 1 —R 2 —N(R 3 )—R 4 —R 5  wherein R 1  is a substituted or non-substituted phenyl group; R 2  is a hydrocarbon chain comprising 0-4 carbon atoms; R 3  is a hydrocarbon chain comprising 1-3 carbon atoms; R 4  is a hydrocarbon chain comprising 1-5 carbon atoms; and R 5  is OH or H. The invention also comprises a separation matrix, comprising the described ligands coupled to a porous support, such as particles or a membrane. The ligand and matrix according to the invention is useful for purification of biomolecules or organic compounds, such as proteins, polypeptides, DNA etc. An advantageous use according to the invention is the purification of antibodies.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/984,132 filed Jan. 4, 2011, which is a continuation of U.S. patentapplication Ser. No. 11/577,208 filed Apr. 13, 2007, now U.S. Pat. No.7,867,784, which is a filing under 35 U.S.C. §371 and claims priority tointernational patent application number PCT/SE2005/001592 filed Oct. 21,2005, published on Apr. 27, 2006, as WO 2006/043896, which claimspriority to patent application numbers 0402558-1 filed in Sweden on Oct.21, 2004 and 0402910-4 filed in Sweden on Nov. 26, 2004.

FIELD OF THE INVENTION

The present invention relates to novel chromatography ligands, which areuseful for the purification of biomolecules such as proteins. Thepresent ligands are useful e.g. for the purification of antibodies,preferably immobilised to a porous support such as particles or amembrane. Consequently, the invention also encompasses a chromatographymatrix comprising the novel ligands, a method for the preparationthereof and a kit for the purification of antibodies.

BACKGROUND OF THE INVENTION

The immune system is composed of many interdependent cell types thatcollectively protect the body from bacterial, parasitic, fungal, viralinfections and from the growth of tumour cells. The guards of the immunesystem are macrophages that continually roam the bloodstream of theirhost. When challenged by infection or immunisation, macrophages respondby engulfing invaders marked with foreign molecules known as antigens.This event, mediated by helper T cells, sets forth a complicated chainof responses that result in the stimulation of B-cells. These B-cells,in turn, produce proteins called antibodies, which bind to the foreigninvader. The binding event between antibody and antigen marks theforeign invader for destruction via phagocytosis or activation of thecomplement system. A number of different classes of antibodies, alsoknown as immunoglobulins, exist, such as IgA, IgD, IgE, IgG, and IgM.They differ not only in their physiological roles but also in theirstructures. From a structural point of view, IgG antibodies have beenextensively studied, perhaps because of the dominant role they play in amature immune response. Polyclonal antibodies are produced according tostandard methods by immunisation of an animal with the appropriateantigen. In response, the animal will produce antibodies which arepolyclonal. However, for many purposes, it is desired to have a singleclone of a certain antibody, known as monoclonal antibodies. Monoclonalantibodies (MAbs) are produced by hybrid or fused cells comprised of afusion between a normal B-cell, which produces only a single antibody,to an abnormal myeloma tumour cell. The resulting hybrid, known as ahybridoma, is these days used in standard methods for the production ofantibodies.

The biological activity that the immunoglobulins possess is todayexploited in a range of different applications in the human andveterinary diagnostic, health care and therapeutic sector. In fact, inthe last few years, monoclonal antibodies and recombinant antibodyconstructs have become the largest class of proteins currentlyinvestigated in clinical trials and receiving FDA approval astherapeutics and diagnostics. Complementary to expression systems andproduction strategies, efficient purification protocols are required toobtain highly pure antibodies in a simple and cost-efficient manner.

Traditional methods for isolation of immunoglobulins are based onselective reversible precipitation of the protein fraction comprisingthe immunoglobulins while leaving other groups of proteins in solution.Typical precipitation agents are ethanol, polyethylene glycol, lyotropicsalts such as ammonium sulphate and potassium phosphate, and caprylicacid. Typically, these precipitation methods are giving very impureproducts while at the same time being time consuming and laborious.Furthermore, the addition of the precipitating agent to the raw materialmakes it difficult to use the supernatant for other purposes and createsa disposal problem, which is particularly relevant when speaking oflarge-scale purification of immunoglobulins.

An alternative method for isolation of immunoglobulins ischromatography, which embraces a family of closely related separationmethods. The feature distinguishing chromatography from most otherphysical and chemical methods of separation is that two mutuallyimmiscible phases are brought into contact wherein one phase isstationary and the other mobile. The sample mixture, introduced into themobile phase, undergoes a series of interactions with the stationary andmobile phases as it is being carried through the system by the mobilephase. Interactions exploit differences in the physical or chemicalproperties of the components in the sample. These differences govern therate of migration of the individual components under the influence of amobile phase moving through a column containing the stationary phase.Separated components emerge in the order of increasing interaction withthe stationary phase. The least retarded component elutes first, themost strongly retained material elutes last. Separation is obtained whenone component is retarded sufficiently to prevent overlap with the zoneof an adjacent solute as sample components elute from the column.Efforts are continuously being made to design the optimal stationaryphase for each specific separation purpose. Such a stationary phase iscommonly comprised of a support or base matrix to which a ligandcomprising functional i.e. binding groups has been attached. Referenceis commonly made to each kind of chromatography based on the principleof interaction it utilises, such as affinity chromatography, hydrophobicinteraction chromatography and ion-exchange chromatography.

Affinity chromatography is based on specific interactions between atarget biomolecule and a biospecific ligand according to a principle oflock-key recognition. Thus, the target and ligand will constitute anaffinity pair, such as antigen/antibody, enzyme/receptor etc.Protein-based affinity ligands are well known, such as Protein A andProtein G affinity chromatography which are both widespread methods forisolation and purification of antibodies. It is well known that ProteinA chromatography provides an outstanding specificity, particularlytowards monoclonal antibodies, and consequently high purities areobtainable. Used in combination with ion exchange, hydrophobicinteraction, hydroxyapatite and/or gel filtration steps, Protein A-basedmethods have become the antibody purification method of choice for manybiopharmaceutical companies, see e.g. WO 8400773 and U.S. Pat. No.5,151,350. However, due to the peptide bonds of the proteins, protein Amatrices present a certain degree of alkaline sensitivity. In addition,when Protein A matrices are used to purify antibodies from cell culturemedia, proteases originating from the cells may cause leakage of ProteinA, or peptide fragments thereof.

Ion exchange chromatography is frequently used in protocols for theisolation of immunoglobulins. In anion exchange chromatography,negatively charged amino acid side chains of the immunoglobulin willinteract with positively charged ligands of a chromatography matrix. Incation exchange chromatography on the other hand, positively chargedamino acid side chains of the immunoglobulin will interact withnegatively charged ligands of a chromatography matrix.

Hydrophobic interaction chromatography (HIC) is another method describedand used in protocols for the isolation of immunoglobulins. If a highlypure immunoglobulin product is the object, it is commonly recommended tocombine HIC with one or more further steps. In HIC, in order to make theimmunoglobulin bind efficiently to the HIC matrix, addition of lyotropicsalts to the mobile phase is required. The bound immunoglobulin issubsequently released from the matrix by lowering the concentration oflyotropic salt. Thus, a disadvantage of this procedure is the necessityto add lyotropic salt to the raw material, as this may cause problemsand a consequently increased cost to the large-scale user. For example,for raw materials such as whey, plasma, and egg yolk, the addition oflyotropic salts to the raw materials would in many instances beprohibitive in large-scale applications, as the salt could prevent anyeconomically feasible use of the immunoglobulin depleted raw material.An additional problem in large-scale applications would be the disposalof several thousand litres of waste.

U.S. Pat. No. 5,945,520 (Burton et al) discloses mixed modechromatographic resins which exhibit a hydrophobic character at the pHof binding and a hydrophilic and/or electrostatic character at the pH ofdesorption. The resin is specifically designed to bind the targetcompound from an aqueous solution at both a low and high ionic strength.This is achieved by selected ionisable ligands comprising a spacer armand at least one ionisable functionality, wherein the density of theionisable ligands on the solid support matrix is greater than thesmaller of either about 150 μmol/mL resin or 1 mmol/gram dry weight ofresin. In addition, the hydrophobic character of the resin comprisingsaid ionisable ligands is sufficient to bind at least 50% of the targetcompound in an aqueous medium at high and low ionic strength at a firstpH. Illustrative examples of the ionisable functionality are4-(aminomethyl)pyridine, 3-(aminomethyl)pyridine,2-(aminomethyl)pyridine, 1-(3-aminopropyl)-imidazole,2-(aminomethyl)-benzimidazole, 4-(3-aminopropyl)morpholine.

Further, WO 01/38228 (Belew et al.) relates to a method foranion-exchange adsorption wherein thioether anion-exchangers are used toremove a negatively charged substance from a liquid by binding thereof.Each ligand comprises a positively charged nitrogen and a thioetherlinkage at a distance of 1-7 atoms from said charged nitrogen. Thedesired substances, such as cells, parts of cells and substancescomprising peptide structures are adsorbed at salt concentrations in theregion of 0.25M NaCl.

Finally, U.S. Pat. No. 6,702,943 (Johansson et al) discloses a methodfor removal of a target substance from a liquid by adsorption thereof toa matrix carrying a plurality of ligands comprising anion-exchanginggroups and a hydrophobic structure. More specifically, the ligandscontain an aromatic ring in the proximity of the positively chargedanion-exchanging groups. The desired substances are stated to be cells,parts of cells and substances comprising peptide structures. The ligandsdisclosed are denoted “high salt ligands” due to their capability ofadsorbing target substances at high concentrations of salt such as 0.25MNaCl.

However, to optimise a process related to the purification of a specifictarget molecule, unique operating conditions will be required, and thebest separation matrix will vary from case to case. For example, in thebiotech industry, specific processes need to be designed for thepurification of peptides and proteins; nucleic acids; virus etc.Further, in the purification of antibodies, the type of antibody willdecisive for the choice of separation matrix. Thus, there is still aneed in this field of alternative separation matrices to provide a broadspectrum of choices for the purification of the many new products thatare constantly developed.

BRIEF DESCRIPTION OF THE INVENTION

One aspect of the present invention is to provide a novel ligand whichis useful in the separation of antibodies from other components of aliquid.

A specific aspect of the invention is to provide such a ligand, which iscapable of adsorbing contaminating proteins but not the target antibody.

Further aspects and advantages of the invention will appear from thedetailed description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustrative chromatography ligand according to theinvention, namely N-benzyl-N-methyl ethanolamine coupled to a supportvia its amine. FIG. 1 shows the prototype ligand N-benzyl-N-methylethanolamine as immobilised via the nitrogen atom to a support in theform of a bead. The coupled ligand is shown to the left with the linkerschematically drawn; and to the right with an illustrative hydrophiliclinker. In the experimental part, the prototype ligand was coupled tothe 6% agarose matrix SEPHAROSE™ 6 FF (GE Healthcare, Uppsala, Sweden).

FIG. 2 shows a chromatogram of separation of monoclonal antibody on aseparation matrix comprising N-benzyl-N-methyl ethanolamine ligandsimmobilised onto SEPHAROSE™ 6 FF; and for reference, the stronganion-exchanger Q SEPHAROSE™ FF, as described below. FIG. 2 shows achromatogram of sample containing 50 mg Mab1 applied to separationmatrices comprising ligands of N-benzyl-N-methyl ethanolamineimmobilised on SEPHAROSE™ 6 FF (901035A); N,N-dimethylbenzylamineimmobilised on SEPHAROSE™ 6 FF; and Q SEPHAROSE™ FF in 25 mM Bis-Tris,100 mM NaCl (˜12 mS/cm), pH 6.5. Elution was performed with 25 mMBis-Tris, 0.5 M NaCl, pH 6.5.

FIGS. 3 a and 3 b show the results of chromatography carried out onligand prototypes with a mixture of mAb1-rProtein A. A-buffer was 25 mMBis-Tris, 50 mM NaCl, pH 6.0. The conductivity was approximately 7mS/cm. B-buffer, 0.5 M Na-Acetate, pH 4.0, was used for elution. Flowrate was 0.5 mL/min (150 cm/h). Sample was 10 mg mAb1, 0.10 mg rPrA at aconcentration of 4 mg/ml mAb1 and 1% rProtein A (w/w). 3 a ref. QSEPHAROSE™ FF; and 3 b N-benzyl-N-methylethanolamine, 146 μmol/mL(901035A).

FIGS. 4 a, 4 b and 4 c show the results of analytical size exclusionchromatography (SEC) on sample with MAb 1, 1% rPrA and pooledflow-through and eluate fractions from the chromatographic runs in FIG.3. The blue curve is flow-through (FT) fractions and the red is eluate.More specifically, FIG. 4 a shows a sample of 4 mg/mL mAb1, 0.04 mg/mLrPrA giving 1% (w/w); 4 b shows FT and eluate from FIG. 3 a Q SEPHAROSE™FF; and 4 c shows FT and eluate from FIG. 3 bN-benzyl-N-methylethanolamine, 146 μmol/mL (901035A).

DEFINITIONS

The terms “antibody” and “immunoglobulin” are used interchangeably inthe present specification.

The term “separation matrix” is used herein to denote a materialcomprised of a support to which one or more ligands comprisingfunctional groups have been coupled. The term “resin” is sometimes usedfor a separation matrix in this field.

The term “multi-modal” separation matrix refers to a matrix capable ofproviding at least two different, but co-operative, sites which interactwith the compound to be bound. For example, one of these sites may givean attractive type of charge-charge interaction between the ligand andthe substance of interest. The other site may give electronacceptor-donor interaction and/or hydrophobic and/or hydrophilicinteractions. Electron donor-acceptor interactions include interactionssuch as hydrogen-bonding, π-π, cation-π, charge transfer, dipole-dipole,induced dipole etc. “Multi-modal” separation matrices are also known as“mixed mode” separation matrices.

The term “surface” means herein all external surfaces, and includes inthe case of a porous support outer surfaces as well as pore surfaces.

The term “eluent” is used in its conventional meaning in this field,i.e. a buffer of suitable pH and/or ionic strength to release one ormore compounds from a separation matrix.

The term “capture step” refers in the context of liquid chromatographyto the initial step of a separation procedure. Most commonly, a capturestep includes clarification, concentration, stabilisation and asignificant purification from soluble impurities. After the capturestep, an intermediate purification may follow, which further reducesremaining amounts of impurities such as host cell proteins, DNA,viruses, endotoxins, nutrients, components of a cell culture medium,such as antifoam agents and antibiotics, and product-related impurities,such as aggregates, misfolded species and aggregates.

The term “disposable” means herein in the context of chromatographycolumns and other separation matrices a matrix which is intended forsingle use, or a limited number of uses. Disposable products areadvantageously used to remove contaminants which are harmful even invery small amounts, in which case it is convenient to adsorb saidcontaminant to the matrix and then discard the matrix. Another situationwhen disposable products are desired is for sterile processing, in whichcase the matrix is sterile or at least aseptic.

The term “polishing step” refers in the context of liquid chromatographyto a final purification step, wherein trace impurities are removed toleave an active, safe product. Impurities removed during the polishingstep are often conformers of the target molecule or suspected leakageproducts.

The term an “Fc-binding protein” means a protein capable of binding tothe crystallisable part (Fc) of an antibody and includes e.g. Protein Aand Protein G, or any fragment or fusion protein thereof that hasmaintained said binding property.

DETAILED DESCRIPTION OF THE INVENTION

In a first aspect, the present invention is a chromatography ligandcomprising an aromatic ethanolamine. The ligand according to theinvention is especially useful in the purification of antibodies, aswill be discussed in more detail below.

In a first embodiment, the present ligand is defined by the followingformula

R₁—R₂—N(R₃)—R₄—R₅

whereinR₁ is a substituted or non-substituted aromatic ring system, such as aphenyl group;R₂ is a hydrocarbon chain comprising 0-4 carbon atoms;R₃ is a hydrocarbon chain comprising 1-3 carbon atoms;R₄ is a hydrocarbon chain comprising 1-5 carbon atoms; and

R₅ is OH or H.

As appears from the above, the group R₁ is connected to the amine via acarbon chain R₂ that may comprise no carbon atoms, i.e. constitute abond between R₁ and the amine; or 1-4 carbon atoms, such as 2-3 carbonatoms, which are optionally substituted. The carbon chain R₄ connectingthe amine with the R₅ may comprise 1-5 carbon atoms, such as 2-4 carbonatoms, which are optionally substituted. R₃ of the amine may comprise1-3 carbon atoms, such as 2 carbon atoms, which are optionallysubstituted.

The aromatic ring system R₁ may comprise one or more substituted ornon-substituted phenyl groups, provided the substitution(s) do notimpair the binding properties of the ligand to any substantial extent.Thus, R₁ may comprise one or more aromatic rings, for instance aphenylene, a biphenylene or a naphthylene structure and other aromaticring systems. Aromatic rings may be heterocyclic, i.e. contain one ormore nitrogen, oxygen or sulphur atoms, for instance a pyridine,pyrimidine, pyrrole, imidazole, thiophene, or pyran. Illustrativesubstituted R₁ groups are selected from the group consisting ofhydoxyphenyl (2-, 3- and 4-); 2-benzimadozolyl; methylthioxyphenyl (2-,3- and 4-); 3-indolyl; 2-hydroxy-5-nitrophenyl; aminophenyl (2-, 3- and4-); 4-(2-aminoethyl)phenyl; 3,4-dihydroxyphenyl; 4-nitrophenyl;3-trifluoromethylphenyl; 4-imidazolyl; 4-aminopyridine;6-aminopyrimidyl; 2-thienyl; 2,4,5-triaminophenyl; 4-aminotriazinyl; and4-sulphoneamidophenyl.

In an advantageous embodiment, R₁ is non-substituted phenyl. In analternative embodiment, R₁ is phenyl substituted with one or more OHgroups.

Further, one or more of R₁, R₂, R₃, and R₄ may be substituted with anysuitable substituent, as long as the binding properties of the ligandare not impaired to any substantial extent. For example, if a morehydrophilic ligand is desired, it may comprise one or more hydrophilicgroups, such as OH groups. Alternatively, substitution may increase thehydrophobicity of the ligand, in which case the ligand may comprise oneor more hydrophobic groups, such as alkyl and/or fluorine. Finally,substitution may be used to introduce one or more additionalfunctionalities, such as charged entities, too increase the multi-modalcharacter of the ligand. Further, the carbon chains R₂ and R₃ may belinear or branched, as long as the branches do not impair the bindingproperties of the ligand to any substantial extent.

In a specific embodiment of the present ligand, R₂ is —CH₂—. In anotherembodiment, R₃ is —CH₃. In a further embodiment, R₄ is —CH₂—CH₂—CH₂— or—CH₂—CH₂—. In yet another embodiment, R₁ is non-substituted phenyl.

Thus, in an advantageous embodiment, the ligand according to theinvention comprises N-benzyl-N-methyl ethanol amine (BMEA). In analternative embodiment, the ligand is N,N-dimethylbenzylamine.

The ligand according to the invention is easily synthesised by theskilled person in this field using standard methods in organicchemistry.

A further aspect of the invention is a method of preparing a separationmatrix, which method comprises immobilising a plurality of ligands asdescribed above to a support. In order to provide a matrix suitable forsingle use especially in the medical or diagnostic field, the separationmatrix prepared according to the invention is also sterilised in asubsequent step. Thus, in one embodiment, the method comprises preparinga matrix as described above; providing the matrix so prepared in acolumn; and sterilizing the matrix so prepared. Sterilization is easilycarried out under suitable conditions by the skilled person in thisfield, such as be heat treatment; radiation; or any other conventionallyused method.

As appears from the formula above, in its non-immobilised state, theligand according to the invention comprises a tertiary amine which willconstitute a suitable handle for coupling the thereof to a support, thuscreating a coupled ligand which comprises a quaternary amine and aphenyl group. Consequently, as immobilized, the ligand according to theinvention is considered to be a multi-modal anion exchange ligand, sincein addition to the positively charged quaternary amine group it alsocomprises the aromatic ring structure which is hydrophobic. Methods forimmobilisation of ligands to porous or non-porous surfaces are wellknown in this field; see e.g. Immobilized Affinity Ligand Techniques,Hermanson et al, Greg T. Hermanson, A. Krishna Mallia and Paul K. Smith,Academic Press, INC, 1992. In one embodiment, the ligands density at thesurface of the support is in a range close to what is commonly used forconventional ion-exchange matrices.

In an advantageous embodiment, the coupling of the ligand to the supportis provided by introducing a linker between the support and linker. Thecoupling may be carried out following any conventional covalent couplingmethodology such as by use of epichlorohydrin; epibromohydrin;allyl-glycidylether; bis-epoxides such as butanedioldiglycidylether;halogen-substituted aliphatic substances such as di-chloro-propanol; anddivinyl sulfone. These methods are all well known in the field andeasily carried out by the skilled person.

In a specific embodiment, the ligand according to the invention iscoupled to the support via a longer linker molecule, also known asextender. Extenders are well known in this field, and commonly used toincrease sterically the distance between ligand and support. Extendersare sometimes denoted tentacles or flexible arms, for a more detaileddescription of possible chemical structures, see e.g. U.S. Pat. No.6,428,707, which is hereby included herein via reference. In brief, theextender may be in the form of a polymer such as a homo- or a copolymer.Hydrophilic polymeric extenders may be of synthetic origin, i.e. with asynthetic skeleton, or of biological origin, i.e. a biopolymer with anaturally occurring skeleton. Typical synthetic polymers are polyvinylalcohols, polyacryl- and polymethacrylamides, polyvinyl ethers etc.Typical biopolymers are polysaccharides, such as starch, cellulose,dextran, agarose.

The support may be made from an organic or inorganic material, and maybe porous or non-porous. In one embodiment, the support is prepared froma native polymer, such as cross-linked carbohydrate material, e.g.agarose, agar, cellulose, dextran, chitosan, konjac, carrageenan,gellan, alginate, pectin, starch, etc. The native polymer supports areeasily prepared and optionally cross-linked according to standardmethods, such as inverse suspension gelation (S Hjertén: Biochim BiophysActa 79(2), 393-398 (1964). In an especially advantageous embodiment,the support is a kind of relatively rigid but porous agarose, which isprepared by a method that enhances its flow properties, see e.g. U.S.Pat. No. 6,602,990 (Berg) or SE 0402322-2 (Berg et al.). In analternative embodiment, the support is prepared from a synthetic polymeror copolymer, such as cross-linked synthetic polymers, e.g. styrene orstyrene derivatives, divinylbenzene, acrylamides, acrylate esters,methacrylate esters, vinyl esters, vinyl amides etc. Such syntheticpolymers are easily prepared and optionally cross-linked according tostandard methods, see e.g. “Styrene based polymer supports developed bysuspension polymerization” (R Arshady: Chimica e L'Industria 70(9),70-75 (1988)). Native or synthetic polymer supports are also availablefrom commercial sources, such as GE Healthcare, Uppsala, Sweden, forexample in the form of porous particles. In yet an alternativeembodiment, the support is prepared from an inorganic polymer, such assilica. Inorganic porous and non-porous supports are well known in thisfield and easily prepared according to standard methods.

Suitable particle sizes of the present separation matrix may be in thediameter range of 5-500 μm, such as 10-100 μm, e.g. 20-80 μm. In thecase of essentially spherical particles, the average particle size maybe in the range of 5-1000 μm, such as 10-500. In a specific embodiment,the average particle size is in the range of 10-200 μm. The skilledperson in this field can easily choose the suitable particle size andporosity depending on the process to be used. For example, for a largescale process, for economical reasons, a more porous but rigid supportmay be preferred to allow processing of large volumes, especially forthe capture step. In chromatography, process parameters such as the sizeand the shape of the column will affect the choice. In an expanded bedprocess, the matrix commonly contains high density fillers, preferablystainless steel fillers. For other processes other criteria may affectthe nature of the matrix.

Thus, a second aspect of the present invention is a separation matrixwhich comprises the ligands described above coupled to a support. Asunderstood by the skilled person in this field, each support willcommonly comprise a plurality of ligands. In a specific embodiment, thesupport comprise a ligand as described above in combination with asecond kind of ligand, wherein the ligand according to the invention ispresent to at least about 30%, preferably at least about 50%, morepreferably at least about 70% and most preferably at least about 90% ofthe total ligand amount. Such a combined ligand separation matrix may bedesigned for a specific case, where an element of further interactionsimprove its separation properties. The second kind of ligand maycomprise one or more charged groups, such as a cation exchanger used toelute compounds by charge repulsion; hydrophobic groups; groups capableof hydrogen-bonding; affinity groups or the like.

In a first embodiment, the matrix according to the invention is in theform of particles, such as essentially spherical, elongated orirregularly formed particles. In a specific embodiment, the separationmatrix is dried, such as dried particles which upon use are soaked inliquid to retain their original form. In an illustrative embodiment,such a dried separation matrix is comprised of dried agarose particles.However, the matrix according to the invention may alternatively takeany other shape conventionally used in separation, such as monoliths;filters or membranes; capillaries; chips; surfaces; etc. Consequently,in a second embodiment, the matrix comprises a membranous structure,such as a single membrane, a pile of membranes or a filter.

A third aspect of the present invention is the use of the separationmatrix described above. In a first embodiment, the present inventionuses a separation matrix as described above in protein purification. Inan advantageous embodiment of the present use, the protein is anantibody; an antibody fragment; or a fusion protein comprising anantibody. In another embodiment, the present invention uses a separationmatrix as described above in the separation of any other compound, e.g.one selected from the group consisting of polypeptides; nucleic acids,e.g. DNA, RNA or oligonucleotides thereof, plasmids; virus; prions;cells, such as prokaryotic or eukaryotic cells; lipids; carbohydrates;organic molecules, such as small organic molecules; drug targets;diagnostic marker molecules. The use will be discussed in more detailbelow. In yet another embodiment, the present invention uses aseparation matrix as described above as support in cell culture, i.e. toimmobilise cells that grow at surfaces. As the skilled person in thisfield will realise, in the present application, the term separation isused for purification; isolation; and removal of compounds, but it alsoencompasses identification of a target compound such as for diagnosticpurposes.

A fourth aspect of the present invention is a method of separation,wherein a desired compound such as an antibody is separated from one ormore other compounds of a liquid sample by contacting a mobile phasecomprising said liquid sample with a separation matrix as describedabove. In an advantageous embodiment, the present method is carried outusing the principles of liquid chromatography, i.e. by passing a mobilephase over a chromatography column comprising the separation matrixaccording to the invention. In another alternative embodiment, thepresent method is carried out using a batch-wise chromatography process,wherein the separation matrix is added to a vessel comprising the liquidsample. In a specific embodiment, the separation matrix added inbatch-wise mode comprises dried particles, such as dried agaroseparticles. In another embodiment, the method is carried out using theprinciples of expanded bed chromatography i.e. by adding the mobilephase to an expanded bed, such as a fluidised bed, of a separationmatrix which is in the form of essentially spherical particlescomprising high density filler.

In a first embodiment of the present method, undesired compounds areadsorbed to the separation matrix while the desired compound, such asthe antibodies, remain in the mobile phase without being adsorbed. Asunderstood by the skilled person in this field, the nature and identityof the adsorbed compounds will depend on the origin of the liquidsample. Examples of compounds adsorbed in the embodiment where desiredantibodies are not adsorbed are cells and cell debris; proteins andpeptides; nucleic acids, such as DNA and RNA; endotoxins, viruses,residues from the culture media etc. In a specific embodiment, thepresent separation matrix is provided in a chromatography column and themobile phase is passed across said column by gravity and/or pumping, theantibodies being recovered in the flow-through of the column. Thus, anadvantage of this embodiment is that it does not require any elution ofthe antibody product from the column. Avoiding a specific elution stepis attractive from a process point of view, since fewer steps willresult in a more rapid purification protocol and consequently reduce theprocess costs. In addition antibodies are sensitive to certainconditions that would e.g. impair their folding pattern; or degrade themby attacking their peptide bonds. Thus, even though elution conditionsfor anion-exchangers in general do not involve any extreme chemicals,the change of salt and/or pH may affect the sensitive antibody, theeffect varying from species to species depending on the pI, chargedistribution etc. Consequently, another advantage of this embodiment isthat it avoids adding an eluent and applying eluting conditions to thedesired compounds. To obtain the most suitable conditions for adsorptionof compounds, the liquid sample is combined with a suitable buffer orother liquid to provide a mobile phase. The present embodiment isadvantageously run under conditions conventional for anion-exchangechromatography, which commonly involves adsorption at a relatively lowsalt concentration. Thus, in one embodiment of the present method, theconductivity of the mobile phase is in the range of 0-25, such as 10-15mS/cm. In one embodiment, the pH of the mobile phase is about 5-6. If itis desired to subsequently release the adsorbed compounds, e.g. forre-use of the matrix, elution may be carried out at a higher saltconcentration, e.g. by use of an increasing salt gradient. The pH valuemay also or alternatively be shifted, e.g. be a decreasing pH gradient,to elute adsorbed compounds.

In a second and alternative embodiment of the present method, thedesired compounds are adsorbed to the matrix as in conventional liquidchromatography. The matrix may then be reused after selective elution ofthe product. Elution is easily performed by passing an appropriatebuffer over the column. If required, one or more washing steps may beapplied before or between any such passage(s). In one embodiment, theoperating conditions of this embodiment are as in conventional ionexchange, i.e. adsorption using a mobile phase having low conductivityand elution by using a high conductivity buffer, as discussed above. Theskilled person in this field can easily tune the conditions by testingdifferent conditions and analyse the adsorbed compound(s) andflow-through. In a specific embodiment, the desired compounds areantibodies.

Choosing between the first and the second embodiment above, the skilledperson in this field can easily adapt the conditions to adsorb aspecific compound, advantageously by control of the pH and/orconductivity. For example, in the separation of antibodies, differentclasses of antibodies have different charges and charge distributionpatterns, which together with the purpose of the separation will decideif it is more preferable to adsorb the antibodies or to let them passthe column without being adsorbed.

The antibodies separated according to one embodiment of the presentinvention may originate from any well known source, such as cellscultured at a surface or from batch-wise or continuous cell culture infermentation tanks or vessels. Thus, in one embodiment, the liquid is asupernatant obtained from cell fermentation. Examples of compounds thatantibodies need to be separated from are then proteins, DNA, viruses,endotoxins, nutrients, components of a cell culture medium, such asantifoam agents and antibiotics, and product-related impurities, such asmisfolded species and aggregates. The step of contact between the mobilephase and the present separation matrix, i.e. the adsorption step, maybe preceded by a step of mechanical filtration, centrifugation and/orchromatography. For example, if the liquid sample is a fermentationbroth, it is advantageous to mechanically remove cell debris, wholecells and other relatively large components before the step using thepresent matrix.

In one embodiment, the present method constitutes the capture step of apurification protocol. In a specific embodiment, the liquid sample is acrude feed which is filtrated before contact with the chromatographymatrix according to the invention. Consequently, this embodiment wouldstill constitute a capture step, even though the liquid sample has beenprepurified by mechanical means. As is well known, the host cells thatproduce antibodies will also comprise a number of other proteinscommonly known as host cell proteins (HCP). Such HCPs include enzymes,such as proteases, and other proteins produced by the host cells. Thus,in one embodiment, substantially all host cell proteins of the liquidsample are removed by the present method, such as by adsorption to theseparation matrix.

In alternative embodiments, the present method is used as a second,third or even fourth chromatography step in a cleaning protocol, such asan intermediate purification or polishing step. Thus, in one embodiment,the mobile phase applied to the present separation matrix comprises anantibody-containing eluate from a separation matrix. In one embodiment,the liquid sample is an eluate from a preceding affinity chromatographymatrix. In an advantageous embodiment, the separation matrix from whichthe eluate is obtained comprises one or more Fc-binding protein ligands,such as Protein A ligands. The term protein A ligands includes in thiscontext native as well as recombinant protein A, or functional fragmentsthereof. In this context, the term “functional” fragment means afragment that has retained the original binding properties of theprotein. Such affinity matrices are commercially available, such asMABSELECT™ from GE Healthcare. Consequently, in this embodiment, theremoved, preferably adsorbed compound may be one or more selected fromthe group that consists of released Protein A; complexes formed betweenProtein A and antibodies, such as Protein A-MAb complexes, whichcomplexes may comprise a number of antibodies per Protein A molecule,such as 2-4 antibodies complexed with one Protein A molecule; andaggregates of released Protein A or antibodies. As the skilled person inthis field will understand, depending on the specific conditions used inthe preceding step, such as affinity chromatography, the eluate may needconditioning by suitable additions or adjustment. Thus, the eluate iscombined with a suitable buffer or liquid to provide a mobile phase.

The present method is useful to separate any monoclonal or polyclonalantibody, such as antibodies originating from mammalian hosts, e.g.mice, rodents, primates and humans, or antibodies originating fromhybridomas. In one embodiment, the separated antibodies are human orhumanised antibodies. The antibodies may be of any class, i.e. selectedfrom the group that consists of IgA, IgD, IgE, IgG, and IgM. In oneembodiment, the antibodies are antibodies capable of binding to ProteinA, or Fc-containing antibody fragments or fusion proteins. In a specificembodiment, the antibodies are immunoglobulin G (IgG), such as IgG1. Inone embodiment, the present method is used to purify antibodies having apI in the range of 6-9, such as in the range of 7-8. In a specificembodiment, the pI of the purified antibodies is about 9. In the presentcontext, it is to be understood that the term “antibodies” also includesantibody fragments and any fusion protein that comprises an antibody oran antibody fragment. Thus, the present invention also encompasses theseparation of fragments of any one of the above mentioned antibodies aswell as fusion proteins comprising such antibodies. In one embodiment,the antibodies are monoclonal antibodies. In a specific embodiment, theantibodies are humanised antibodies.

As appears from the above, in the present method, a substantially purefraction of non-adsorbed antibodies is recovered. In this context, theterm “substantially pure” is understood to mean that substantially allthe non-antibody compounds have been removed. Most advantageously, atleast about 80%, such as at least about 95%, i.e. in the interval of95-100%, such as at least about 98%, i.e. in the interval of 98-100% andpreferably at least about 99%, i.e. in the interval of 99-100%, of thetotal amount of contaminants is removed on the present separationmatrix. However, as the skilled person in this field will appreciate,the purity obtained will depend on the concentration of antibody in theliquid sample applied to the separation matrix as well as otherconditions used. Thus, in one embodiment, the antibodies separatedaccording to the present method are antibodies of therapeutic grade.Thus, the antibodies purified according to the invention are useful inresearch and also for the preparation of antibody pharmaceuticals, suchas MAb drugs. An alternative use of the purified antibodies is fordiagnostic use. Further, the purified antibodies are also useful in foodproducts such as food additives for humans. For example, bovineantibodies purified according to the present invention are useful infood products.

In a specific embodiment of the present method, the present separationmatrix is provided as a disposable chromatography column or a disposablefilter. An advantage of using disposable products in a method forpurification of therapeutic compounds such as antibodies is that itenables avoiding cross-contamination between two different processes.Thus, in one embodiment, the present separation matrix is provided as asterile chromatography column or filter. In one embodiment, the presentmethod is carried out as a batch-wise process, wherein a disposableseparation matrix is added to a vessel comprising the liquid from whichthe antibodies are to be recovered. A suitable time is allowed fortarget compounds to adsorb to the matrix, after which the liquid phasecomprising the antibodies is removed from the vessel. The used matrixmay then be disposed of, without releasing the adsorbed compounds, whichagain may be advantageous from a safety point of view since compoundssuch as endotoxins and/or certain host cell proteins need not be handledany further. In an alternative embodiment, the present matrix isprovided as a disposable product in a chromatography column which isused in a mode wherein the antibodies are adsorbed. In an advantageousembodiment, the column and matrix have been sterilized, allowing theuser to purify antibody product under aseptic or even sterileconditions.

In a second aspect, the present invention relates to a kit for thepurification of antibodies from one or more other components in aliquid, which kit comprises in separate compartments a chromatographycolumn packed with a separation matrix as described above; one or morebuffers; and written instructions. The separation matrix may be asdescribed above. Said instructions advantageously describe a method asdefined above in detail.

EXAMPLES

The present examples are provided for illustrative purposes only, andshould not be interpreted in any way as limiting the scope of theinvention as defined by the appended claims.

Example 1 Preparation of Separation Matrix According to the InventionPreparation of BMEA SEPHAROSE™ Fast Flow

One embodiment of the method of preparing a separation matrix accordingto the invention is shown below, starting from a crosslinked agarose gel(SEPHAROSE™ 6 Fast Flow, GE Healthcare, Uppsala, Sweden).

A. Introduction of Allyl Group on the Matrix

SEPHAROSE™ 6 Fast Flow was activated with allyl glycidyl ether asfollows: 100 ml of SEPHAROSE™ 6 Fast Flow was suction dried, mixed with0.3 g of NaBH₄, 12 g of Na₂SO₄ and 35 ml of 50% aqueous solution ofNaOH. The mixture was stirred for 1 hour at 50° C. After addition of 100ml of allyl glycidyl ether the suspension was left at 50° C. undervigorous stirring for an additional 16 hours. After filtration of themixture, the gel was washed successively, with 500 ml distilled water,500 ml ethanol, 200 ml distilled water 200 ml 0.2 M acetic acid and, 500ml distilled water. Titration gave a degree of substitution of 0.22 mmolof allyl/ml of gel.

B. Activation of Allyl SEPHAROSE™ 6 Fast Flow Via Bromination

Bromine was added to a stirred suspension of 50 ml of allyl activatedSEPHAROSE™ 6 Fast Flow (0.22 mmol allyl groups/ml drained gel), 1 g ofsodium acetate and 15 ml of distilled water, until a persistent yellowcolour was obtained. Sodium formate was then added until the suspensionwas fully decolourised. The reaction mixture was filtered and the gelwashed with 500 ml of distilled water. The activated gel was thendirectly transferred to a reaction vessel and further reacted withN-benzyl-N-methylethanolamine.

C. Introduction of BMEA (N-benzyl-N-methylethanolamine) Groups on theActivated Matrix

The amine groups were introduced on the matrix directly via the nitrogenatom of the amine groups. In a typical procedure, the coupling to thematrix was realised via bromination of the allyl group and nucleophilicsubstitution under basic conditions. 25 ml of bromine activated gel(0.22 mmol allyl groups/ml drained gel) was transferred to a reactionvial containing a solution of N-benzyl-N-methylethanolamine (16.0 ml). 5ml of water was added and the pH of the reaction solution was adjustedto 12.0 with sodium hydroxide solution. The reaction was left for 16hours under stirring at 50° C. After filtration of the reaction mixturethe gel was successively washed with 3×10 ml of distilled water, 3×10 mlaqueous 0.5 HCl and finally 3×10 ml of distilled water. BMEA SEPHAROSE™Fast Flow gel was obtained with a degree of substitution of 0.15 mmolamines/ml of gel.

Example 2 Purification of Antibodies in the Flow-Through Example 2A)Disposition

Under non-binding conditions, sample containing approximately 50 mg mAb1 were loaded onto prototype 901035 A (N-benzyl-N-methyl ethanolamine)at approximately 5 and 12 mS/cm. Flow-through fractions (FT) werecollected at 5, 10 and 15 column volumes (CV). Fractions from theelution peak were pooled. FT fractions were analysed for HCP and ProteinA content.

To confirm that the chromatographic performance was not unique for oneparticular mAb, the chromatographic runs were repeated using a samplecontaining mAb2 at pH 6.0 and approximately 12 mS/cm. The performance ofthe prototype was first evaluated with analytical SEC. Selectedfractions were analysed for HCP and Protein A content. After screeningthe fractions with SEC selected fractions were sent for HCP and ProteinA analysis.

To test the rProtein A clearance of the prototype, MAb1 was spiked with1% (w/w) recombinant Protein A (rPrA). The prototype was injected with asample volume corresponding to 10 mg MAb1, 1% rProtein A at pH 6.0 and aconductivity of approximately 7 mS/cm. Flow-through and eluate fractionswere pooled separately and analysed with SEC.

Materials/Investigated Units

Columns and gels were obtained from GE Healthcare, Uppsala, Sweden

HIPREP ™ 26/10 Desalting cat. no. 17-5087-01 CV = 53.09 mL TRICORN ™5/50 cat. no. 18-1163-09 CV = 1 mL HR 5/5 ™ cat. no. 18-0338-01 CV = 1mL SUPERDEX ™ 200 10/300 GL, cat. no. 17-5175-01 CV = 23.56 mL

Instruments

Chromatography systems: ÄKTAExplorer™ 10

Spectrophotometer SPECTRAMAX® Plus Chemicals

All chemicals used were of analytical grade. Water wasMILLI-Q®-filtered.

Chromatography Media

Q SEPHAROSE™ Fast Flow (FF) (GE Healthcare, Uppsala, Sweden). Theligands of the separation matrices are prototypes as described in Table1 below.

TABLE 1 Ligand Cl⁻ capacity Prototype ref. Ligand (μmol/mL) 901035AN-benzyl-N-methyl 146 ethanolamine

Samples

Two different humanised IgG antibodies, subclass 1, denoted MAb 1 andMAb 2, with an extinction coefficient of 1.46 and 1.50 respectively,were used. Both antibodies were expressed in a CHO cultures andsubsequently purified using conventional Protein A affinitychromatography prior to the present experiments.

Buffer exchange was made on a HIPREP™ Desalting column (GE Healthcare,Uppsala, Sweden), equilibrated with the buffer of interest, by injectingan appropriate volume (5-15 mL) with a SUPERLOOP™ (GE Healthcare,Uppsala, Sweden). The flow rate was 5 mL/min and fractions of 5 mL werecollected. Fractions containing the eluted peak were pooled and theabsorbance at 280 nm determined in duplicates, in order to calculate theconcentration according to equation 1:

A ₂₈₀ =ε·C·l  (Eqn 1)

wherein

-   -   A₂₈₀ is the absorbance at 280 nm.    -   ε (mL*mg*cm⁻¹) is the extinction coefficient for a particular        protein.    -   C (mg/mL) is the concentration of the protein.    -   l (cm) is the path length.

Size exclusion chromatography (SEC) was performed on a SUPERDEX™ 20010/300 column (GE Healthcare, Uppsala, Sweden) at a flow rate of 0.5mL/min. The buffer was PBS (phosphate-buffered saline); 10 mM phosphate,0.137 M NaCl, 2.7 mM KCl, pH 7.4 prepared from tablets (Sigma, P-4417).

Method Equilibration 2/0.1 CV; 2 CV first time 0.1 CV between runsSample injection 50 μl use; Isocratic Elution 1.5 CVChromatography on Prototypes with mAb

A-buffer was 25 mM Bis-Tris, pH 6.0 or 6.5. Depending on the desiredconductivity, approximately 5 or 12 mS/cm, 35 or 100 mM NaCl wasincluded. The elution buffer (B-buffer) was 25 mM Bis-Tris, 0.5 M NaCl,pH 6.5. The flow rate was 0.5 mL/min (150 cm/h).

Method: Equilibration 5 CV A-buffer Sample injection 5-25 mL samplecont. 20 or 50 mg mAb Wash 5 CV A-buffer Gradient Elution 10 CV 0-100%B-buffer Elution 10 CV 100% B-buffer Regeneration 5 CV A-bufferChromatography on Prototypes with MAb-rProtein A

A-buffer was 25 mM Bis-Tris, pH 6.0. The conductivity was approximately7 mS/cm by addition of 50 mM NaCl, B-buffer was 0.5 M Na-acetate, pH4.0. Flow rate was 0.5 mL/min (150 cm/h). Sample concentration was 4mg/mL MAb 1-0.04 mg/mL rPrA giving 1% (w/w).

Method: Equilibration 5 CV A-buffer Sample injection 2.5 mL 10 mg MAb,1% rPrA Wash 5 CV A-buffer Gradient Elution 10 CV 0-100% B-bufferElution 10 CV 100% B-buffer Regeneration 5 CV A-buffer

CIP (Cleaning in Place)

After each chromatographic run, the prototype and the reference matrix QSEPHAROSE™ FF were subject to the following CIP procedure;

30% isopropanol 5 CV (Column Volumes) H₂O 5 CV 1.0M NaOH 4 CV (incl. 15min. pause) H₂O 5 CV A-buffer 5 CV H₂O 5 CV 20% EtOH 5 CV

Protein A Analysis

Selected fractions were mixed with SPA sample diluent in proportions of800 μl SPA sample diluent+200 μl sample. After mixing, the fractionswere heated on a heating block at 99° C. for 10 minutes, then mixedagain. The samples were then analysed for recombinant Protein A.

Host Cell Proteins (HCP) Analysis

The samples (min. 600 μl) were analysed for HCP content. The lowerdetection limit is 10 ng/mL.

Example 2B) MAb1-Containing Sample Purified on Prototype LigandsN-Benzyl-N-Methylethanolamine (901035A)

Sample containing 50 mg MAb1 was applied to N-benzyl-N-methylethanolamine immobilised on SEPHAROSE™ 6 FF (901035A) prepared asdescribed in Example 1 above and the reference matrix Q SEPHAROSE™ FF in25 mM Bis-Tris, 100 mM NaCl (˜12 mS/cm), pH 6.5. Elution was carried outwith 25 mM Bis-Tris, 0.5 M NaCl, pH 6.5.

The chromatograms of example 2 are shown in FIG. 2, which shows theprototype N-benzyl-N-methyl ethanolamine SEPHAROSE™ 6 FF (901035A)compared to Q SEPHAROSE™ FF. Flow-through (FT) fractions selected foranalysis are indicated with arrows. The results for HCP and Protein Aclearance shown in tables 2 and 3 below reveal that the prototype issuperior to Q SEPHAROSE™ FF in that respect.

TABLE 2 Results from HCP analysis Start FT1 FT2 FT3 Column pH (ng/mL)(ng/mL) (ng/mL) (ng/mL) Q SEPHAROSE ™ FF 6.5 890 160 200 180 (ref)N-benzyl-N- 6.5 890 10 20 35 methylethanolamine, 146 μmol/mL (901035A)

TABLE 3 Results from PrA analysis Start FT1 FT2 FT3 Column pH (ng/mL)(ng/mL) (ng/mL) (ng/mL) Q SEPHAROSE ™ FF 6.5 0.40 0.69 0.46 0.31 (ref)N-benzyl-N- 6.5 0.40 0 0 0 methylethanolamine, 146 μmol/mL (901035A)

Example 3 Purification of MAb1 in the Flow Through from a SampleComprising MAb1 and Recombinant Protein a (rPrA) on Prototype LigandN-benzyl-N-methylethanolamine

In this example, chromatography on prototypes with a sample containingmAb1-rProtein A was performed. A-buffer was 25 mM Bis-Tris, 50 mM NaCl,pH 6.0. The conductivity was approximately 7 mS/cm. B-buffer was 0.5 MNa-Acetate, pH 4.0. The flow rate was 0.5 mL/min (150 cm/h). Sample was10 mg mAb1, 0.10 mg rPrA at a concentration of 4 mg/ml mAb1 and 1%rProtein A (w/w). The results are shown in FIG. 3.

Finally, analytical SEC on sample with mAb1, 1% rPrA and pooledflow-through and eluate fractions from the chromatographic runs in FIG.4 were performed. The results are shown in FIG. 4. In FIG. 4 a, theshaded peak is the complex of MAb1-Protein A.

The blue curve is the flow-through (FT) fractions and the red is theeluate.

Example 4 Adsorption Mode 4A) Disposition

To test the selectivity of BMEA SEPHAROSE™ Fast Flow (BMEA;N-benzyl-N-methylethanolamine) in adsorptive mode the retention time ofhuman IgG and eight different proteins was tested. The results werecompared to a commercially available anion exchanger Q SEPHAROSE™ FastFlow. The principle of the test method was that proteins were injectedinto an HR5/5 column (containing the BMEA ligands immobilised onSEPHAROSE™ Fast Flow) equilibrated with the A-buffer (containingpiperazine as buffer component). A salt gradient was used for elution ofthe proteins (see method below).

Materials/Investigated Units

Columns and Q SEPHAROSE™ Fast Flow were obtained from GE Healthcare,Uppsala,

Sweden.

HR 5/5 ™: cat. no. 18-0338-01 Column Volume (CV = 1 mL)

Instrument

Chromatography systems: ÄKTAExplorer™ 10

Chemicals and Samples

The proteins, ovalbumin, β-lactoglobulin, bovine serum albumin,α-lactalbumin, myoglobin, lactoferrin, ribonuclease A and cytochrome Cwere purchased from Sigma and human IgG (Gammanorm) was purchased fromOctapharma. The proteins were dissolved in the A-buffers at aconcentration of 1-10 mg/ml. Q SEPHAROSE™ Fast Flow was obtained from GEHealthcare, Uppsala Sweden. All chemicals used were of analytical gradeand the water used was MILLI-Q®-filtered.

Chromatography

The columns were equilibrated with the A-buffer at a flow rate of 0.6ml/min before 100 ml of the sample solution were applied. Only oneprotein at a time was analysed. The proteins were eluted by a lineargradient from buffer A to buffer B with a gradient volume of 21 columnvolumes (see method below). The buffer A was 25 mM Piperazine, pH 10.0and buffer B was 25 mM Piperazine, 1.0 M NaCl, pH 10.0. The absorbanceat 280 nm was detected during all runs.

Method: Equilibration: 5 CV of A-buffer Sample injection: 100 μl (ca 0.2mg protein) Gradient: 21 CV 100% B-buffer Equilibration 5 CV of A-bufferafter gradient:

Results

To document if the BMEA ligand interact selectively withimmunoglobulines, human IgG was applied to a 1 ml column (HR 5/5) packedwith the new medium. In addition, the proteins ovalbumin,β-lactoglobulin, bovine serum albumin, α-lactalbumin, myoglobin,lactoferrin, ribonuclease A and cytochrome C were also applied. Theresults were compared with the retention times of the proteins observedfor Q SEPHAROSE™ Fast Flow. Q SEPHAROSE™ Fast Flow is a stronganion-exchanger and is used as reference anion exchanger since it hasthe same support matrix (support material, bead size, pore sizes, porevolume, packing procedure etc) and has essentially the same substitutiondegree (measured as ion exchange capacity). As appears from Table 1 BMEASEPHAROSE™ Fast Flow retarded all the investigated proteins morestrongly compared with Q SEPHAROSE™ Fast Flow. Furthermore, IgG was theprotein that gave the longest retention time with BMEA SEPHAROSE™ FastFlow (Table 1). This reflects a much stronger binding to the BMEA mediumthan to Q SEPHAROSE™ Fast Flow. Compared to Q SEPHAROSE™ Fast Flow theretention time of IgG increased 27.3 min when BMEA SEPHAROSE™ Fast Flowwas used (Table 1). These results clearly indicate that BMEA SEPHAROSE™Fast Flow can be used to capture and elute IgG in a selective way.

TABLE 1 Retention time (t_(r)) of different proteins on Q SEPHAROSE ™Fast Flow and BMEA SEPHAROSE ™ Fast Flow. t_(r) on Q t_(r) on BMEASEPHAROSE ™ SEPHAROSE ™ Δt_(r) Molecular Fast Flow Fast Flow (t_(r)BMEA− Protein weight pI (min) (min) t_(r)Q) Cytochrome C 12400 9.6 15.3 16.81.5 Ribonuclease A 13700 9.4 15.8 22.6 6.8 Lactoferrin 75000 7.9 15.119.4 4.3 Myoglobin 17600 7.2 16.1 20.5 4.4 Human IgG 160000 16.5 43.827.3 α-Lactalbumin 14400 5.2 24.6 40.3 15.7 Bovine serum 69000 5.1 25.332.6 7.3 albumin β-Lactoglobulin 35000 5.1 25.1 37.1 12.0β-Lactoglobulin 35000 5.1 30.0^(x) 37.1 7.1 Ovalbumin 43500 4.7 21.830.8 9.0 na = not analyzed, ^(x)Two peaks were observed

The above examples illustrate specific aspects of the present inventionand are not intended to limit the scope thereof in any respect andshould not be so construed. Those skilled in the art having the benefitof the teachings of the present invention as set forth above, can effectnumerous modifications thereto. These modifications are to be construedas being encompassed within the scope of the present invention as setforth in the appended claims.

1. A chromatography ligand defined by the following formula:R₁—R₂—N(R₃)—R₄—R₅ wherein R₁ is a substituted or non-substituted phenylgroup; R₂ is a hydrocarbon chain comprising 0-4 carbon atoms; R₃ is ahydrocarbon chain comprising 1-3 carbon atoms; R₄ is a hydrocarbon chaincomprising 1-5 carbon atoms; and R₅ is OH or H.
 2. The ligand of claim1, wherein one or more of R₁, R₂, R₃, and R₄ are substituted with OH. 3.The ligand of claim 1, wherein R₁ is a non-substituted phenyl group. 4.The ligand of claim 1, wherein R₂ is —CH₂—.
 5. The ligand of claim 1,wherein R₃ is —CH₃.
 6. The ligand of claim 1, wherein R₄ is—CH₂—CH₂—CH₂— or —CH₂—CH₂—.
 7. The ligand of claim 1, comprisingN-benzyl-N-methyl ethanol amine.
 8. A method of preparing a separationmatrix comprising immobilising a plurality of ligands of claim 1 to asupport.
 9. The method of claim 8, wherein the ligand is immobilised viathe amine group.
 10. The method of claim 8, wherein the support isporous.
 11. A separation matrix comprising ligands of claim 1 coupled toa support.
 12. The matrix of claim 11, wherein the support comprisesparticles, such as substantially spherical particles.
 13. The separationmatrix of claim 11, wherein the support comprises a membranousstructure.
 14. A method of manufacturing a chromatography columncomprising: preparing the matrix of claim 11; providing the matrix soprepared in a column; and sterilizing the column comprising the matrix.15. A method of manufacturing a separation membrane comprising:preparing the membrane of claim 13; and sterilizing the membrane. 16-17.(canceled)
 18. A method of separating one or more antibodies from one ormore other compounds in a liquid sample, wherein a mobile phasecomprising said antibodies and compound(s) is contacted with theseparation matrix of claim
 11. 19. The method of claim 18, wherein theseparation matrix is provided in a chromatography column, the mobilephase is passed across said column by gravity and/or pumping, and theantibodies are recovered in the flow-through of the column.
 20. Themethod of claim 18, wherein the liquid sample comprises a supernatantobtained from cell fermentation.
 21. The method of claim 18, wherein thecontact with the separation matrix is preceded by a step of mechanicalfiltration and/or chromatography.
 22. The method of claim 18, whereinthe liquid sample comprises a crude feed.
 23. The method of claim 18,wherein the adsorbed compound(s) are host cell proteins andsubstantially all said proteins are adsorbed to the separation matrix.24. A kit for the purification of antibodies from one or more othercomponents in a liquid, which kit comprises, in separate compartments, achromatography column packed with the separation matrix of claim 11; oneor more buffers; and written instructions.
 25. A disposablechromatography column for the purification of antibodies, which columncomprises the separation matrix of claim
 11. 26. The column of claim 25,which has been sterilised.
 27. The separation matrix of claim 11,wherein one or more of R₁, R₂, R₃, and R₄ are substituted with OH. 28.The separation matrix of claim 11, wherein R₁ is a non-substitutedphenyl group.
 29. The separation matrix of claim 11, wherein R₂ is—CH₂—.
 30. The separation matrix of claim 11, wherein R₃ is —CH₃. 31.The separation matrix of claim 11, wherein R₄ is —CH₂—CH₂—CH₂— or—CH₂—CH₂—.